The global program to eliminate lymphatic filariasis (GPELF) is based on the expectation that 4 to 6 annual mass drug administrations (MDA) will reduce LF morbidity to an acceptable level and interrupt transmission, thereby leading to extinction of LF. This strategy is based on as yet limited data from field settings where the burden of LF infection and morbidity are high. Our long terms goals are to assess the proscribed GPELF strategy has been sustained in an area of Papua New Guinea where we have previously nearly completed eliminated LF infection and transmission with four annual cycles of MDA, evaluate in new populations whether integration of MDA with vector control enhances morbidity control and transmission elimination, and under what levels of LF endemicity these complementary interventions are most effective. The specific aims are: 1.To determine the long-term impact of the currently recommended GPELF MDA strategy on reduction of LF morbidity and infection. We will determine whether reduction/elimination of LF-related disease and human infection indicators resulting from 4 consecutive rounds of MDA are sustained 7 to 8 years after cessation of any systematic intervention. 2.To quantify the added benefit of vector control (insecticide impregnated mosquito nets, ITN) to MDA (annual single dose DEC plus albendazole) on Anopheles mosquito-transmitted Wuchereria bancrofti. This aim compares changes in LF morbidity and infection following institution of ITN plus MDA or MDA alone in previously untreated residents of high transmission and moderate transmission areas. 3. To estimate the impact of MDA and ITN on infection levels and transmission of soil transmitted helminths and associated co-morbidities. This aim determines whether MDA that includes albendazole increases the well being of school children, and the possible emergence of parasite resistance against benzimidazole in MDA-treated populations. This work complements parallel studies of the mosquito vector and provides empirical data for mathematical modeling of LF ecology and eradication. Results of these inter-related projects will inform public health policy not only in Papua New Guinea but also other areas of the world where both LF and malaria are transmitted by Anopheles mosquitoes, such as sub-Saharan Africa.